1. Field of the Invention
This invention relates generally to the field of telecommunications, and more particularly to methods by which telephone calls (either via a personal computer or conventional xe2x80x9cblack telephonexe2x80x9d set) are placed between two parties over a packet switched computer network such as the internet. In accordance with one aspect of the invention, the method facilitates automated mapping of called party telephone numbers with the network addresses of IP telephony gateways that serve those numbers.
2. Description of the Related Art
This invention is related to the emerging technology presently known as internet telephony (sometimes referred to in the art as Voice over IP (VoIP) or IP Telephony, where IP stands for Internet Protocol) and the process by which digitized voice is treated as data and routed over a digital data network between the call""s participants. The invention is particularly suitable for use in devices or systems that support the handling of IP telephony calls. An example of one such device is the IP telephony gateway or internet telephony gateway (ITG), which is where IP telephony calls are typically created and terminated on the network. Of course, the invention is also suitable for use in other devices or systems as well.
Internet telephony presents an attractive technology for use in long distance telephone calls, as compared to the public switched telephone network (PSTN), which has been the traditional transmission medium. The primary advantage is cost. In the United States, long distance service providers for the PSTN provide domestic services at rates ranging from roughly 10 to 30 cents per minute, and international rates for substantially more, depending on the time of day, day of the week, and the distances involved. In contrast, the cost of internet telephony anywhere in the world is potentially the cost of a local telephone call to the local internet telephony provider at one end and the cost of a local call from an internet telephony service provider at the far end to the destination telephone. Once the call is routed from the local internet telephony provider onto the internet, the transmission of the data from the local internet telephony provider to the far end internet telephony provider can be free for all practical purposes, regardless of where the two parties are located. The same holds true whether the call is sent over the internet or over a private data network.
Those skilled in the art are familiar with the typical configuration of an internet telephony system. In general, users at two or more telephone devices are set to engage in a conversation over an IP network. Each telephone device (and/or phone number) is typically served by an ITG, which is owned and operated by an internet telephony service provider (ITSP) and which provides connectivity to the network. To place an internet telephony call, a party contacts an ITG of his or her ITSP (xe2x80x9cthe originating ITGxe2x80x9d) and provides the telephone number of a called party. The originating ITG then sets up a call over the IP network with an ITG that serves the called party (xe2x80x9cthe terminating ITGxe2x80x9d), and the terminating ITG then contacts the called party, thus completing the communications path between the calling and called parties. Once this path has been established, the parties may begin to engage in interactive telephone communication over the IP network.
This basic IP telephony, arrangement assumes that the originating ITG knows the IP network address of the terminating ITG that serves the called party and therefore knows where in the network to route calls placed to the called party telephone number. However, when a person places an IP telephony call, the person may typically supply the originating ITG with only the telephone number of the called party (and perhaps an authorization code), not the IP address of the terminating ITG that serves the called party. Therefore, in order to facilitate completion of the call, some mechanism must be in place to allow the originating ITG to determine the IP address of an appropriate terminating ITG based on the telephone number of the called party.
In existing IP telephony systems, this address mapping functionality is provided by an address mapping system (AMS). The AMS is typically positioned as at least one node on the IP network, and each ITG in the network can establish IP communication with the AMS. The AMS typically includes database server coupled with one or more address mapping databases. The to address mapping databases then include one or more tables of data that correlate telephone numbers with the IP addresses of ITGs serving those numbers. Thus, when an originating ITG receives a call request, the ITG may transmit a signaling message over the IP network to the AMS, asking the AMS to translate the dialed telephone number into an IP address of an ITG that can provide network connectivity for the called party. The AMS may then consult its address mapping database tables and return a response message to the querying ITG, indicating the IP address of a terminating ITG. The originating ITG may then set up the call with the terminating ITG.
The existence of a commercially useful address mapping system assumes in turn that the AMS will contain substantially current and correct mapping information for correlating telephone numbers with IP addresses. Therefore, some mechanism must be provided for populating the address mapping database(s) with this mapping information. One such mechanism is rote-force data entry, in which, for example, an operator sits at a computer workstation and enters countless records, one for each telephone number or group of telephone numbers in the network. Of course, this manual data entry process can be exceedingly time consuming and error prone. Further, as telephone numbers and IP addresses are added, removed or changed, the data records in the address mapping database(s) must be updated accordingly. Consequently, there exists a need for an improved mechanism of populating the AMS with address mapping information.
The present invention provides a method and system for automatically discovering and registering the IP addresses of IP telephony gateways and the corresponding phone numbers of subscribers served by those IP telephony gateways.
In accordance with one aspect of the invention, a self registering IP telephony gateway (SRITG) may be provided. The SRITG may include a microprocessor, a memory and a network interface unit and may be configured to automatically convey mapping indicia to an AMS in the network. This mapping indicia may include, for instance, (i) indicia of the IP address of the SRITG (xe2x80x9cIP address indiciaxe2x80x9d) and (ii) indicia of the phone numbers that the SRITG serves (i.e., xe2x80x9cphone number indiciaxe2x80x9d). In one arrangement, for instance, the SRITG may be configured to automatically convey this information to the AMS when the SRITG is first installed and powered up, and/or in response to a change in its IP address or in the phone numbers that it serves.
In accordance with an aspect of the invention, the SRITG may convey its mapping indicia to the address mapping machine via an IP network transmission, via a conventional PSTN modem-to-modem connection, or via another suitable connection. Further, the SRITG may convey the mapping indicia to the AMS either directly (for instance, as a data or payload message delivered to the AMS) or indirectly (for instance, as an indicator that allows the AMS to derive the necessary information, for instance, based on readily available reference databases).
By way of example, the IP address indicia may literally be the IP address of the SRITG. Alternatively, the IP address indicia may be a domain name of the company that owns and/or operates the SRITG, and the AMS may translate that domain name into a numerical IP address of the SRITG by reference to a readily available Domain Naming System (DNS) server.
Also by way of example, the phone number indicia may literally be the phone numbers served by the SRITG. Alternatively, the phone number indicia may simply be the phone number of the SRITG itself, and the AMS may identify the phone numbers geographically closest to the SRITG phone number, and therefore likely served by the SRITG, by reference to a readily available geographic phone number mapping database. Further, according to another advantageous feature of the present invention, the SRITG may easily convey its own phone number to the AMS by placing a conventional PSTN call to the AMS and letting the AMS receive its phone number via standard calling number delivery (xe2x80x9ccaller IDxe2x80x9d) processes.
Still alternatively, the phone number indicia may be the specific geographic position of the SRITG, and the AMS may identify phone numbers geographically closest to that position, and therefore likely to be served by the SRITG, by reference to a readily available geographic phone number mapping database. In this regard, in accordance with another useful aspect of the present invention, the SRITG may determine its specific geographic coordinates through readily available Global Positioning System (GPS) information and may convey those coordinates to the AMS through any suitable connection.